"This site ist a part of the bigcompany.com. Other Projects are site1.bigcompany.com and anothersite.com."

Is that a good idea or would you rather put those links on one single page, like the imprint or about page?

(In Germany you have to have a link to your imprint on every single page of your website, so its common to have a footer with a lot of legal stuff, how to book ads on this site, Copyright Information and so on.)